稳定渗流条件下土坡稳定性分析的一种新方法

在提出随机角生成曲线滑动面方法的基础上,通过改变选定参数来搜索临界滑动面,对渗流作用下的不同士质边坡进行稳定性分析.考虑渗流效应时,将士体视为三种土条划分情况,并进行受力分析,推导出简化Janbu法中土条的浮力和渗透力计算公式.同时,对实际渗流场做出合理简化,以便应用于计算机编程.算例对比分析表明:①此方法计算出的最小安全系数与已有研究成果非常接近,得到的最危险滑动面也颇为相似,可证明本文方法的正确性;②以非圆弧滑动面与圆弧滑动面计算出的最小安全系数相比,前者明显要小,建议在有渗流作用时应采用非圆弧滑动面;③对两个不同水位下的均质土坡,以水位与坡高之比为参数对边坡状态进行分析时,结果表明随着地下水位的升高,边坡安全系数急剧下降,因而,渗流效应是边坡发生失稳的一个重要因素,工程实际中应特别注意边坡排水设施的设置.     

引入退火机制的智能单粒子算法在复杂边坡最危险滑动面搜索中的应用

复杂边坡的安全系数可能存在多个局部极小值点,如何确定边坡的最小安全系数是复杂边坡稳定性分析中的一个关键问题.本文结合简化Bishop法,采用一种新的启发式全局优化算法--智能单粒子算法(ISP0)来搜索复杂边坡的最危险滑动面.为帮助该算法快速跳出局部极值点,本文将模拟退火(SA)机制引入到智能单粒子算法中,结合了两种算法各自的优点,提出了引入退火机制的智能单粒子算法SA-ISPO.将本文提出的SA-ISPO算法用于搜索两个复杂边坡的最危险滑动面,并与其它方法相比较,验证了SA-ISPO算法的优越性,该算法搜索效率高,计算结果不受搜索范围的影响,是一种较好的全局优化算法.     

泸沽湖机场高填方边坡动稳定性分析

泸沽湖机场存在高填方边坡,由于机场地处高烈度地震区域,应重视地震作用对填方边坡稳定性的影响。为此选取典型地质剖面,建立相应地质模型,运用软件Geo-Studio的Sigma模块,建立有限元模型,用传统条分法搜索出最不利滑动面位置,最后运用Geo-Studio的Quake模块进行动稳定性计算,并采用Newmark法对填方边坡进行动稳定性评价,最后给出有效提高边坡稳定性的地基处理建议。     

基于赤平投影法对某锌铟矿边坡稳定性分析

岩质边坡的失稳和破坏主要是受岩体中结构面所控制,赤平投影法可以直观地判断各结构面的组合和切割关系,可用来进行岩质边坡稳定性分析。在简要介绍赤平投影基本原理的基础上,根据赤平投影及实体比例投影对云南某露天锌铟矿边坡进行了稳定性分析和运动学分析,并且在原手工画图的基础上采用CAD画图的方式,既方便又快捷,而且根据各结构面对边坡整体划分了区域,最后应用赤平投影法对某边坡稳定性做出评价。     

某大型露天矿山边坡稳定性分析

充分收集资料,分析与总结已有矿区地质资料,进行现场调查,复核研究区区域地质构造、地层分布,岩性特征等地质数据。调查区域地质构造,查清节理、断层、光面的产状,分析结构面的产状对边坡稳定性的影响,并进行统计分析。综合调查结果,开展现状边坡稳定性分析,并针对西源岭290m以上边坡治理提出有效的措施和建议。     

基于模糊综合评价的露天矿山边坡稳定性分析

边坡的稳定性分析具有不确定性。以模糊数学为理论基础,建立了露天矿山边坡稳定性分析的模糊综合评价体系,并将建立的体系应用于某露天铜矿边坡稳定性分析,结果表明:评价效果较好,能反映边坡所处的实际状态,具有实用性,可为露天矿山边坡稳定性分析提供借鉴。     

基于优势结构面的矿山边坡稳定性分析

针对露天边坡的稳定性问题,首先利用玫瑰花图和极点等密度图对结构面产状进行统计分析,然后结合边坡的地形地貌、地层岩性以及结构面发育程度等多方面因素得出对边坡稳定性起控制作用的优势结构面,并采用赤平极射投影对边坡的稳定性进行定性分析。结果表明,利用优势结构面判断矿山边坡是否稳定具有一定的可行性。     

某工业区山体滑坡稳定性分析及工程治理

根据西乡固戍第三工业区山体滑坡区域地质条件和边坡体的基本特征,分析诱发滑坡的主要原因,并对滑坡体稳定性进行定性分析。通过反演计算,确定饱和状态下滑动面强度参数,利用传递系数法对滑坡进行稳定性评价和剩余推力计算;根据计算结果,采用削坡减载、抗滑桩、预应力锚索、锚索(杆)格构梁等措施对边坡进行综合治理。监测结果表明,在后期连续强降雨情况下,滑坡体变形稳定,治理效果良好。     

南芬露天铁矿冯家东沟排土场滑坡稳定性分析

排土场的稳定性是影响露天矿安全生产的重要因素,排土场的稳定性日益成为露天矿山最为关注的问题之一。在南芬露天铁矿,冯家东沟排土场是一高台阶的排土场,以前发生过滑坡和泥石流事件,因此,对其影响排土场边坡稳定性的各种因素和工程地质条件进行了调查并采用极限平衡理论中Sarma分析方法,对冯家东沟排土场边坡的稳定性进行了系统研究,主要对冯家东沟目前情况下,可能产生浅层滑坡、深层滑坡、沿原始坡面滑坡及基层岩体滑动等各种可能发生的破坏进行了系统地分析,得出了当排水疏干工作比较完善时,边坡不会产生沿原始坡面的整体性滑坡。然而,边坡内富集了地下水时,整体滑坡也有可能形成;按目前的边坡赋存条件,边坡不可能产生在基岩内部的滑动的结论。     

某铜矿露采边坡稳定性及边坡角优化研究

以某大型铜矿为例,针对露天开采过程中遇到的边坡稳定性和边坡角优化问题进行了研究,考虑边坡岩体自重和地下水的影响采用极限平衡法对该铜矿进行稳定性分析,应用Geostudio岩土工程分析软件进行边坡角的优化,得到最小的安全系数,使边坡稳定性的评价更趋符合实际,以保证开采的安全性及满足生产能力的要求。     

兰尖铁矿露天采场边坡稳定性研究

以兰尖铁矿露天转地下开采为工程背景,针对尖包包矿区露天采场边坡稳定性问题,利用简化Bishop法,对露天采场的边坡稳定性进行分析。通过数值模拟分析,得出选取的典型边坡剖面的安全系数,并确定边坡最危险滑裂面的位置。研究结果表明,兰尖铁矿尖包包矿区露天采场的边坡是稳定的。     

基于随机响应面法的金鸡岭岩质边坡可靠度分析及抽样方法对比

结合有限元滑面应力法和Hermite随机响应面法建立了金鸡岭岩质边坡稳定可靠度非侵入式分析模型，在此基础上研究了均匀设计抽样、LHS抽样、改进LHS抽样和分层抽样4种抽样配点方法对随机响应面的拟合精度、边坡失效概率及安全系数统计特征的影响。结果表明：（1）金鸡岭岩质边坡未支护状态下的失效概率约为18.4%，失稳风险较大，需采取支护加固措施；（2）改进LHS抽样和LHS抽样所构造的随机响应面具有较好的拟合精度，抽样配点效果优于分层抽样和均匀设计抽样；（3）建议边坡可靠度非侵入式随机分析采用改进LHS抽样或LHS抽样进行随机响应面的抽样配点计算，并尽可能多地选取样本点以外的验算点对随机响应面拟合精度进行校验。     

New Method for 3D and Asymmetrical Slope Stability Analysis

A new three-dimensional (3D) slope stability analysis method is developed based on two-directional moment equilibrium. This method calculates not only the safety factor but also the possible direction of sliding for semispherical and composite failure surfaces. As a result, the possible errors associated with assuming a plane of symmetry in 3D stability analyses are eliminated. Another advantage of the new method is to eliminate the tedious work on the coordinate transformation prior to the analysis. Two examples of symmetrical failure surfaces are used to verify the basic formulation in the present study. Three additional examples further demonstrate the applicability of the proposed method in analyzing 3D asymmetrical failure surfaces. An analysis on a slope, subject to asymmetrical excavation unloading and geological conditions, shows that using the method of one-directional moment equilibrium may give an overestimated safety factor of the slope.     

Generalized Method for Three-Dimensional Slope Stability Analysis

This paper describes an extension of a new three-dimensional (3D) stability analysis method, including formulation, comparative studies, and examples of new application. The new method uses “two-directional force and moment equilibrium” in the stability analysis of 3D potential failure mass with arbitrary shapes. The use of this new method has resulted in a novel situation wherein the direction of the resultant shear force (or direction of sliding) generated on the potential failure surface can now be calculated instead of the guesswork assumptions that were formerly made. It is also demonstrated that this new method eliminates the labor-intensive work for establishing local coordinate systems performed in conventional 3D analysis. Consequently, this new method facilitates a computer-aided 3D search for the critical failure surfaces in slope areas.     

Quantitative Risk Assessment of Cut-Slope Projects under Construction

In some cut-slope projects landslide is a common problem during construction due to unfavorable geomorphological and geomechanical conditions. It is necessary to do a quantitative assessment of the risk posed by landslide before determining the budget or tender price. This paper outlines a general procedure for doing this, followed by an example to demonstrate the approach in comparison to a known failure. Finite-element analyses identify the most dangerous landslide scenario among all construction steps. The slope failure probability is then estimated using reliability theory based on the most dangerous construction step. After identifying the potential failure surface and estimating the volume of the sliding mass, the runnout behavior of sliding mass is simulated to delimit the extent of likely impacted area. Then, the exposed elements at risk and their vulnerabilities are identified and analyzed. The landslide risk is assessed quantitatively for three types of consequences: casualties, economic loss, and time overrun. Compared with actual consequences, the estimation results were in acceptable agreement with the case study. The paper demonstrates that it is feasible to analyze the risk associated with landslides during construction of cut-slopes.     

Seismic Stability of Soil Retaining Walls Situated on Slope

Many soil retaining walls, which were used to stabilize highway embankments constructed on hillside, were severely damaged during the major earthquake (Chi-Chi earthquake, ML = 7.3) on September 21, 1999 in Taiwan. We investigated two typical cases of soil retaining wall damage using survey, soil borings and soil tests. To this end we developed a new pseudo-static method to evaluate the seismic stability of retaining walls situated on slope. Sliding failure along the wall base and bearing capacity failure in the foundation slope were considered in the new pseudo-static method. Results of the analysis showed that seismic stability of the wall against bearing capacity failure may be greatly overestimated when the inertia of soil mass is not taken into account. The analytical results also showed that sliding failure along the wall base occurs prior to the bearing capacity failure of the wall situated on a gentle slope at Site 1. The opposite is true for the wall situated on a steep slope at Site 2. For soil retaining walls constructed on slope, sliding failure of the wall may occur under small input horizontal ground acceleration when the passive resistance in front of the wall is not effectively mobilized. This highlights the importance of improving the strength of backfilled soils in the passive zone when constructing soil retaining walls on slope. The results obtained in the present study also suggest a modification of the current design considerations for soil retaining walls situated on slope.     

指定界面边坡稳定分析方法的改进

垃圾填埋场场底防渗系统经常作为软弱层需要分析沿其界面的稳定性,目前常用软件不能直接用于分析,需要对输入的模型进行改进,以求稳定分析更真实地反应出边坡在指定界面处的安全系数。     

Dimensionality and Directionality Effects in Newmark Sliding Block Analyses

Newmark sliding block analyses represent a useful and practical tool for evaluation of seismic slope stability hazards. The analysis requires assumptions about material and failure surface behavior that have been well documented in the literature. This paper investigates the effects of assumptions about the manner in which loading is applied on the results of the analysis. The common practice of applying a one-dimensional input motion parallel to the plane of the sliding block model was compared with the application of two- and three-dimensional input motions for sliding block models with frictional and cohesive failure surfaces; the differences were found to be small for some cases and large for others—in both conservative and unconservative directions. The effect of slope azimuth on Newmark sliding block displacements was also investigated. Computed displacements were found to be very sensitive to the assumed azimuthal direction of the input motion, particularly for cases of high yield acceleration. Procedures for estimating azimuthal variability are presented.     

Incipient Motion of Riverbank Sediments with Outflow Seepage

Based on a force analysis, an expression is derived to describe the critical Shields number for incipient motion of uniform cohesionless sediment particles on a riverbank slope in terms of flow parameters, outflow seepage, and physical and mechanical properties of sediments. Parametric studies were conducted to investigate quantitatively the effects of hydraulic gradient of seepage, slope angle, and flow direction on the critical Shields number. The results show that the critical Shields number decreases with an increase in the hydraulic gradient. Where bank collapse is concerned, the most dangerous direction of hydraulic gradient of outflow seepage is at an angle equal to the effective internal angle of friction of the sediment mass with respect to slope surface. At a certain value of hydraulic gradient, the critical Shields number decreases with increasing slope angle. Open flow becomes more erosive when the current direction changes from horizontally parallel with the riverbank line to turning downward.     

银山矿露天边坡稳定性分析

露天边坡稳定性受岩性、岩体结构、水文地质、边坡形态和爆破等多种因素影响。露天矿常见的边坡失稳,滑坡等地质灾害直接威胁露天采场的正常生产。为研究银山矿现有边坡的稳定性,建立了Dimine软件三维模型,采用工程地质分区、极限平衡法分析边坡各种破坏模式下的受力状态,以边坡滑体上的抗滑力和下滑力之间的关系评价边坡的稳定性,分析结果表面银山矿总体边坡较稳定,南部后续开采过程中需加强现场巡视与边坡监测,及时消除安全隐患。